The invention relates to the field of remote motor vehicle starter systems, and more particularly, to the use of battery voltage monitoring to determine the appropriate cut-off voltage of a starter engine.
Starting a car from a distance has its-appeal particularly in extreme weather. There are a variety of devices that can perform this type of operation. An important function of a remote car starter is determining when to stop cranking the starter engine. In a manual starting operation, this corresponds to the release of the key in the ignition from the START position to the ON position. A person performing this action manually can either sense the engine has started from the vibrations of the vehicle or hear the change in sound being emitted from the vehicle.
However, when starting a vehicle from a distance, neither of the two characteristics one relies on to start a car manually can be depended upon. Controlling the cut-off of the starter engine must be done some other way. The timing involved in this particular task is critical to the functionality of the remote control car starter and any slight deviation from the optimal time can have negative effects on the starter as well as the engine of the vehicle.
However, there are certain key features that are important in order for a remote control car starter to be sufficiently practical and properly respond to the needs of the current market. These features are crucial to the optimization of a remote control car starter. The first one is that the remote control starter be simple to install. It is of high importance that the device be simple to install because the installation is often done by the average technician or mechanic and an installation process of high complexity could lead to many problems. The goal is to have the lowest probability of error in the installation process so as to minimize the risk of affecting any other component in the vehicle.
Another key feature is the reliability of the device. The objective of highest possible reliability is hard to achieve when there are many wires that can be affected by such things as corrosion or a short circuit with another wire present under the hood of a car. The third and equally important feature of a remote car starter is that it be universal, i.e. it can work on as many different car models as possible. A starter that is limited to certain models is of little use on the market.
Simplicity, reliability, and adaptability are the issues that must be improved upon in order to properly comply to the needs of the market. It would be ideal to combine these features with a remote control car starter that uses battery voltage sensing techniques to determine start and release times of the starter motor. This particular method reduces the amount of wires present for the remote car starter and simplifies the installation process.
As stated in the Background of the Invention of U.S. Pat. No. 5,905,315 to Lefebvre et al., there are already proposed methods to control the cut-off of the starter engine of a vehicle by monitoring the battery voltage. The proposed method of the aforementioned Patent utilizes a method of voltage sensing of a battery voltage in which the starter is cut-off when the battery voltage reaches a threshold value, this threshold value being a function of the initial battery voltage and a fixed constant K. The constant value K is set to be less than or equal to 1. The initial battery voltage is measured before the starter is activated and a fraction of this value (corresponding to a product of K and the initial voltage) is compared to the battery voltage during the ignition process. The starter is cut-off when the sensed battery voltage reaches a threshold value. This way, when there is a change in the initial battery voltage, there is a corresponding change in the cut-off voltage.
Lefebvre does not disclose how K is calibrated. This makes it difficult to adjust the K value to each car. Since it is unlikely that every vehicle will have the same K value, a fixed K value may work better on some vehicles than others and does not render the device universal.
Accordingly, an object of the present invention is to provide a remote control car starter system with a simplified installation process. Self-programming of the system removes the need to set the starting parameters to any pre-determined value necessary for the starting process. This simplification will reduce the risk of error in the installation process.
Another object of the present invention is to provide a remote control car starter that is reliable in the long run. It is the object of this invention to reduce the number of wires used to connect the device to the other components in the vehicle. This will decrease the risk of a malfunction of the device due to a wire being broken or shorted with another wire and will also contribute to making the installation of the device easier.
Yet another object of the present invention is to provide a remote control car starter that can learn from one or a series of manual starts what should be an appropriate K value. This way, it can adapt itself to a wide variety of different models of vehicles.
In accordance with a first aspect of the present invention, there is provided a method for starting an engine automatically comprising the steps of measuring the battery voltage of a battery powering the starter motor of an engine over time to obtain a measured battery voltage; detecting a manual start of the starter motor; detecting a manual release of the starter motor; calculating a ratio K of the measured battery voltage prior to the manual start to the measured battery voltage at or before the manual release; and during automatic starts, monitoring the battery voltage, starting the starter motor and releasing the starter motor when the battery voltage reaches a value equal to the product of K and the battery voltage sampled prior to starting the starter motor automatically.
In accordance with a second aspect of the present invention, a device is provided for starting an engine automatically comprising a voltage measurer for measuring the battery voltage of a battery powering the starter motor of the engine to obtain a measured voltage; a learn controller for detecting a manual start and a manual release of the starter motor and calculating a ratio K of the measured voltage prior to the manual start to the measured voltage at or before the manual release; a storage device to store the ratio K; a remote start controller for starting the starter engine remotely and releasing the starter engine when the battery voltage reaches a value equal to a product of K and the battery voltage sampled prior to starting the starter motor automatically; and a Transmitter/Receiver (TX/RX) module to transmit and receive signals.